The invention is based on an apparatus for detecting slip of a drive belt between a generator and the drive motor, as generically defined by the preamble to the main claim.
From German Patent Disclosure DE 43 25 505 A1, an electronic control unit for motor vehicles is already known in which the idling rpm of the engine is controlled as a function of the load at the generator. When there is a load on the generator, the idling rpm is raised, while upon relief of the generator the rpm is lowered, to reduce fuel consumption by the motor vehicle. An unfavorable aspect of this control unit is that only an rpm adaptation as a function of the load on the driven generator is done, but not any monitoring whether the torque furnished by the drive motor is in fact transmitted to the shaft of the generator. If drive belt slip occurs, that is, if the V-belt slips on the pulley, then the requisite torque, despite the raising of the idling rpm of the engine, cannot be transmitted and lead to a battery discharge, since the drive belt slip has not been detected and the error can accordingly not be corrected.
The apparatus of the invention for detecting slip of a drive belt of a generator driven by a drive motor, having the characteristics of the body of the main claim, has the advantage that a slipping drive belt (slip) can be detected immediately, and thus advantageously a poor battery charge or a creeping discharge of the battery is avoided over a longer period of time. It is especially advantageous that by detection of the slipping drive belt, problems in the coolant system can be revealed under some circumstances as well, since often the water pump is also driven by the drive belt of the generator.
By the provisions recited in the dependent claims, advantageous refinements of and improvements to the apparatus defined by the main claim are possible.
It is especially advantageous that the load of the generator is also picked up by way of the voltage course at the terminal DF. By the determination of the electrical load acting on the generator, a simple capability is obtained of monitoring the load switched for the sake of the monitoring, such as a fan or some other consumer that is as large as possible. Additional consumers that have been turned on randomly can be detected and eliminated by the comparison with the switched load.
It is also advantageous that the determination of the change in the on-board electrical system voltage is repeated if the comparison with the predetermined limit value leads to an error. By displaying the error or outputting a warning signal, the driver is either immediately told to go to a repair facility, orxe2x80x94depending on its urgencyxe2x80x94the error can be stored in memory and taken care of the next time the vehicle is serviced.
It is also advantageous that the determination of the load of the drive motor is effected at a predetermined rpm, since for this rpm for the predetermined electrical load, only a comparison value has to be stored in memory. If more than one rpm value is used, then advantageously the associated comparison value for each rpm should be stored in memory.
It is also considered especially advantageous that the apparatus is used in the form of a control program in an already existing control unit for engine or vehicle functions. This largely eliminates additional hardware expense.
It is also favorable for an error that has occurred to be stored in a memory of the apparatus, so that it can be read out at any time and battery failure, for instance, caused by a discharge state can thus be explained.